Chem learning and tests

Ammonia

damp red litmus paper turns blue

chlorine

damp litmus paper is bleached

water

anhydrous copper sulfate turns from white to blue

Flame test

Dip wire loop in conc hydrochloric acid then in solid compound then in Bunsen flame

Lithium flame test

Crimson

Sodium flame test

Yellow

Potassium flame test

Lilac

Calcium flame test

Orange-red

Copper flame test

Blue-green

NH4+ (ammonium)

Add NaOH and warm. Test gas given off for ammonia.

Test for common metal cations

Add NaOH

Fe2+

Green precipitate Fe(OH)2

Fe3+

Brown precipitate Fe(OH)3

Cu2+

Blue precipitate Cu(OH)2

Test for halide ions

Add dilute nitric acid. Then silver nitrate.

Cl-

White ppt AgCl

Br-

Cream ppt AgBr

I-

Yellow ppt AgI

Sulfate SO42-

Add dilute HCl then barium chloride solution. White ppt (BaSO4) forms.

Carbonate (CO32-)

Add acid. Test gas given off for CO2

What colour and state is fluorine at room temp?

Pale yellow gas

mols =

mols = conc x vol

vol =

vol = mol x 24

mass

mass = mols x mr

equation for oxygen forming at anode

4OH- → 2H20 + O2 + 4e-

equation for hydrogen forming at cathode

2H+ + 2e- → H2

What colour and state is chlorine at room temp? And what colour is it in solution?

Green gas. Pale green in solution.

What colour and state is bromine at room temp? And what colour is it in solution?

red-brown liquid. orange in solution

What colour and state is iodine at room temp? And what colour is it in solution?

grey solid. dark brown in solution.

What colour and state is iodine if heated?

purple gas

Similarities in reactions of group 1 metals

fizzes (bubbles of gas), moves around

What does potassium do when reacted with water?

Ignites and burns with lilac flame

What do sodium and potassium do when reacted with water?

Melt/dissolves

What are three preventions against rusting?

Barrier methods (e.g. paint, oil)

Sacrificial protection - attaching zinc or magnesium to react instead of iron.

Galvanising - coating in a layer of zinc (barrier + sacrificial)

What colour is litmus in acid?

Red

What colour is litmus in alkali?

Blue

What colour is methyl orange in acid?

red

What colour is methyl orange in alkali?

yellow

What colour is phenolphthalein in acid?

colourless

What colour is phenolphthalein in alkali?

pink

Compounds containing ________ are soluble.

Na+, K+, NH4+, NO3-, Cl-, SO42-

Compounds containing Cl- are soluble except…

AgCl and PbCl2

Compounds containing SO42- are soluble except…

BaSO4, CaSO4 and PbSO4

Compounds containing CO32- are NOT soluble except…

Li2CO3, Na2CO3 and K2CO3

Compounds containing OH- are NOT soluble except…

LiOH, Na

Delta H =

q(kJ)/mol

How does a catalyst work?

Speeds up the rate of reaction by providing an alternative pathway with a lower activation energy.

Characteristics of dynamic equilibrium

Rate of forwards reaction equals rate of backwards reaction.

Concentrations of reactants and products remain constant.

Fractional distillation

Crude oil is heated before entering the fractionating column as vapour.

Column is hotter at bottom and cooler at the top.

Fractions have different boiling points.

Each fraction condenses at its boiling point.

The lowest boiling point fractions condense at the top of the tower.

Refinery gases

Domestic heating and cooking

What is the order of the products of fractional distillation?

Refinery gases

Gasoline

Kerosene

Fuel oil

Bitumen

Going down the fractions they get:

Bigger (longer chain)

Less volatile

More viscous

Darker

Less flammable

Complete combustion of hydrocarbons forms

CO2 and H2O

Incomplete combustion of hydrocarbons forms

CO or C and H20.

How does CO affect the body

Binds to haemoglobin in blood preventing oxygen from getting around the body.

What do alkanes do under UV light?

Undergo substitution reactions with halogens.

Unsaturated

C=C double bond.

Alkenes undergo _____ with halogens

addition reactions

Why is acid rain a problem?

Harms plants + fish + reacts with limestone buildings damaging them.

What are the conditions needed for reacting ethene with steam?

300C, 60-70atm, phosphoric acid catalyst

What is the equation for reacting ethene with steam?

C2H4 + H2O → C2H5OH

Conditions for fermentation of carbohydrates

35C, 1ATM, Yeast catalyst, no oxygen so anaerobic.

Equation for fermentation of carbohydrates

C6H12O6 → 2C2H5OH + 2CO2

What are the benefits of making ethanol by reacting ethene with steam?

Continuous process

Fast

Produces 100% pure ethanol

What are the disadvantages of making ethanol by fermentation of carbohydrates?

Batch process

Slow

Only 15% pure so needs purifying

What are 3 ways ethanol can be oxidised and what do they produce?

Combustion - produces CO2 and H2O

Microbial oxidation - produces ethanoic acid and water

With an oxidising agent of potassium dichromate with sulfuric acid. Potassium dichromate turns from orange to green. - produces ethanoic acid and water.

Carboxylic acid functional group

-COOH

Esters functional group

COO

How are esters made?

When a carboxylic acid reacts with an alcohol with a sulfuric acid catalyst

Ethanol + butanoic acid →

ethyl butanoate + water

Uses of esters

Flavourings and perfumes

How are addition polymers made?

From single monomers added together. No other products are formed.

How are condensation polymers made?

From two monomers and produce water as a by-product.

What are the disposal issues with addition polymers?

They are inert and not biodegradable

They release toxic gases when burnt.

Reactivity series mnemonic

Potassium	P - Powerful
Sodium	S- Scrum-halves
Lithium	L - Love
Calcium	C - Crushing
Magnesium	M - Massive
Aluminium	A - Attackers
Carbon	C - Centres
Zinc	Z - Zoom
Iron	I - Into
Hydrogen	H - Hard
Copper	C - Collisions
Silver	S - Scoring
Gold	G - Greatly

Soluble salt from insoluble reactant

-Add insoluble reactant to acid whilst heating until excess solution.

-Filter using paper, and heat filtrate using evaporating basin

-Once a concentrated solution, let cool for crystals to form

-Remove crystals and dry with filter paper.